Improvement of image quality is an extremely important problem in a printing process. Because of this, conventionally and continuously various kinds of techniques have been developed. On the other hand, recently, it has become general practice that various objects such as characters, drawings, and images (pictures or the like) are contained in a single document.
Under this circumstance, there is a tendency that techniques for improving the image quality become more complex. In other words, if image quality of a certain object among the characters, drawings, images, and others has priority, a problem is that image qualities of other objects may be degraded.
For example, Japanese Laid-Open Patent Application Publication No. 7-214825 describes a technique where the independent selection of halftone processing and the independent selection of color correction are individually executed with respect to various color options for text, graphics and photo images.
However, the technique described in Japanese Laid-Open Patent Application Publication No. 7-214825 does not increase resolution and there is a limitation to the improvement of the image quality. For example, jaggy edge may not be effectively removed.
The increase of the resolution and the capability to perform image processing are in conflict with each other. Therefore, if the resolution is simply increased, the capability to perform image processing may be degraded.